Heavy initial demand a necessary condition for sound money?

I'm currently reading 'The Mystery of Banking' by Murray Rothbard, written in 1983. It's an absolutely amazing read about sound money and the essence of the modern fraudelent banking system. Next to the Bitcoin Standard a must-read for every bitcoiner. Although, Rothbard argues that for sound money to arise, people will pick "a commodity already in widespread use for its own sake", apart from a commodity being highly divisable, portable, durable and having a high value per unit weight. Bitcoin is of no use apart from monetary and thus does not abide by the first rule. Can you refute Rothbard's argument? How do you see Bitcoin's value proposition with respect to this criterion set by Rothbard?